A controller pilot data link communications (CPDLC) human machine interface (HMI) is a set of screens used by members of an aircraft flight crew to receive uplink messages from the air traffic controller and to send downlink messages to the air traffic controller. Today when a pilot of an aircraft wants to change altitude or speed, the pilot talks to the air traffic controller (ATC), typically, via a very high frequency (VHF) radio and asks for the desired altitude or speed. The ATC datalink system (also referred to herein as a CPDLC system) permits the pilot make the request for the desired altitude or speed via a datalink.
One type of CPDLC message that the pilot creates, requests changes to the flight such as a different altitude or a different speed. The air traffic controller, upon receiving the downlink request message, reads it and sends a response. Usually the response grants the request or denies the request. In some cases, the controller may be puzzled by the request and question whether the pilot really meant to send that specific request. In this case the controller has a third response, which is to respond with the “confirm request” uplink. The CPDLC uplink message “confirm request” is alpha-numerically indicated as “UM143” and is sometimes sent responsive to a downlink request message. The air traffic controller sends a confirm request message when there is concern that the wrong value may have been sent in the original message.
The intent of the confirm request message is to trigger a resending of the last downlink request message sent by the pilot. Currently, when the confirm request message is received, the pilot searches for the last downlink request message sent. When the last downlink request message sent is found, the pilot then navigates through air traffic control menu screens, selects the same downlink request message screen, composes the message by filling in the data to match the original downlink request message or revised data, and sends the downlink request message again. This process requires considerable “head-down time” during which the pilot is looking down at the display showing the HMI screens instead of flying the aircraft.
If there is operational urgency in the message being sent, the head-down time adds time to the processing of the message and delays an urgently required action.